Biodegradable polymer materials made of silk fibroin elements are known, for example, from US-A-2004/0005363 (Tsukada et al.). This patent document teaches a composite material made from silk fibroin and another secondary substance, such as cellulose, chitin, chitosan (or derivatives), Keratin or polyvinyl alcohol. The composite material can be used as a sustained release substrate for medicines, a biological cell growth substrate, a metal ion-absorbing material and a biodegradable water-absorbing material.
Another example of a composite material in which proteins coat the surface of a surgical device is disclosed in WO-A-94/22584 entitled “Chronic Endothelial Cell Culture under flow”. In this patent application, the inner lumen of a hollow polypropylene fibre was coated with a synthetic protein polymer Fibronectin F which contains multiple repeats of the RGD fibronectin binding site. This produced an inner lumen surface which was substantially uniformly coated with the synthetic protein polymer on which cells could be grown. The polypropylene fibres can be used in vascular grafts. The strength of the vascular graft is as a result dependent on the tensile strength of the polypropylene fibres.
The surgical device (stent grafts and vascular grafts) described in WOA-01/38373 (Boston Scientific) exploits the strength of spider silk by providing an outer or interstitial sheath over the outside surface or the luminal surface of an inner stent. The inner stent is made from a multitude of materials such as synthetic textile materials, fluoropolymers and polyolefines. Nylon, polyester and polyurethane are often used. These-materials which can not be resorbed by the body. The material of the outer sheath is non-resorbable conventional man-made polymeric material or a combination of spider silk and man made polymeric material.